Here is my 1979 K10 LWB. My daughter named it King Neptune. And since she is the Princess, I have to keep the name.
Specs: 350, th350. NP203. Not sure what axles or gearing. No rust except for surface rust on the rear bumper. Not sure about the floor boards yet. But they feel solid.

I'm closing this thread and opening a new one. This one will still be here but it has gotten to the point of being so large it is draining other resources on the server. The new one cant be found @ How about some pics of '73-'87 Long Beds Part II